Radio frequency (RF) switches are commonly utilized in wireless communication devices (e.g., smart phones) to route signals through transmit and receive paths, for example between the device's processing circuitry and the device's antenna. RF transistors, such as field effect transistor (FET) type RF transistors, can be arranged in a stack in order to improve RF power handling of RF switches.
However, conductive materials and dielectric materials used in RF transistors often contribute to parasitic capacitances associated with RF frequencies. Particularly when RF transistors are in OFF states, these parasitic capacitances can result in significant performance tradeoffs. Further, different power handling requirements may be required for different RF transistors in a stack of transistors in an RF switch, depending on where in the stack a particular RF transistor is positioned. For example, in a wireless transceiver where a stack of RF transistors is situated between an antenna and a power amplifier (PA), or between an antenna and a low noise amplifier (LNA), power handling requirements can depend on the positions of different RF transistors relative to the antenna, the PA, and/or the LNA. Fabricating RF transistors without significant RF performance tradeoffs becomes difficult and complex.
Thus, there is a need in the art for RF transistors with reduced OFF-state capacitances that accommodate different power handling requirements in an RF switch.